1. Field of the Invention
The invention relates to a shortenable umbrella of the folding type.
2. Description of the Prior Art
Positive control of the peripheral dome rib parts, effected in conjunction with the closing and opening movements of a shortenable umbrella, is disclosed, for example, in French Pat. No. 717,989 and in U.S. Pat. Nos. 2,616,439 and 2,649,103.
In the case of designs of this type in French Application No. 7,216,899 and German Disclosure Text No. 2,320,496, inward and outward folding of the outer dome rib part is achieved by means of a control rod. One end of this control rod is connected to the slide strut of the dome rib, while the other end is connected to a carriage running on the central dome rib. The central dome rib is also connected to a transfer member which causes the outer dome rib part to fold outwardly or inwardly. According to one embodiment, this transfer member is in the form of a toothed rack, which cooperates with the corresponding externally toothed eye of this outer dome rib part. According to a variant, a curved member is interposed between the central and outer dome ribs, the curved member engaging with a hinge pin located away from the eye. The carriage on the central dome rib is spring loaded in the sense of opening the dome, but this makes it more difficult to close the umbrella frame. This design is, moreover, relatively complex, and this has a considerable effect upon the manufacturing costs and durability of an umbrella of this kind.